does president obama deserve credit for improving the u.s. economy after a surprisingly strong employment report? i'm wolf blitzer. you're in "the situation room." >>> a ten-day mourning period is under way for one of the most influential leaders of our time. we're learning more about the final tributes to nelson mandela. stand by for that, and for my special conversation with the former president, bill clinton. he reveals a time when he and the south african president didn't see eye-to-eye but first, the breaking news we're following. >>> a brutal winter storm turns deadly. at least four people have been killed on icy roads in the southern u.s. we're seeing a dangerous mix of snow, sleet, freezing rain and bone-chilling cold, and it's creating hazardous conditions from texas to tennessee and beyond. now a one-two punch of weather misery is on the way, affecting both coasts from now through monday. we have team coverage beginning with our meteorologist jennifer gray at the cnn weather center. jennifer, what's going on? >> well, we are getting